Obviously, slavery was one. But it was caused because of the issue on whether or not the area the US was going to expand to, the new states, would be slave or not. South Carolina declared that if Lincoln was elected, they would secede. The South believed that their state rights were being attacked, and they legally had the right to secede. However, Lincoln also did not try hard to hold onto them, he did not punish the first states to secede which allowed the others to. And the strong Abolitionists in the North, though few, were mighty, and scared the Southerners. I'm not entirely sure of your options, but I hope this helps!
Mostly, it was because of slavery and the South fearing that their States Rights would be lost.
la muerte es mia y tu chiguaguah
